diff --git a/src/captiveportal/index.php b/src/captiveportal/index.php
index 818457dee..85787338f 100644
--- a/src/captiveportal/index.php
+++ b/src/captiveportal/index.php
@@ -90,22 +90,25 @@ $passthrumac = isset($cpcfg['passthrumacadd']);
 function ip_to_mac($addr)
 {
 	$cmd = '/usr/sbin/arp -n ' . $addr;
+	$ret = false;
 
 	exec($cmd, $out, $ret);
 	if ($ret) {
 		log_error('The command `' . $cmd . '\' failed to execute');
 	} else {
-		$mac = explode(' ', $out);
+		$mac = explode(' ', $out[0]);
 		if (isset($mac[3])) {
-			return array('macaddr' => $mac[3]);
+			$ret = $mac[3];
 		}
 	}
+
+	return $ret;
 }
 
 /* find MAC address for client */
 if ($macfilter || $passthrumac) {
 	$tmpres = ip_to_mac($clientip);
-	if (!is_array($tmpres)) {
+	if (!$tmpres) {
 		/* unable to find MAC address - shouldn't happen! - bail out */
 		captiveportal_logportalauth("unauthenticated","noclientmac",$clientip,"ERROR");
 		echo "An error occurred.  Please check the system logs for more information.";
@@ -113,7 +116,7 @@ if ($macfilter || $passthrumac) {
 		ob_flush();
 		return;
 	}
-	$clientmac = $tmpres['macaddr'];
+	$clientmac = $tmpres;
 	unset($tmpres);
 }